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1 /* |
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2 * Copyright 2007-2009 Sun Microsystems, Inc. All Rights Reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Sun designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Sun in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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22 * CA 95054 USA or visit www.sun.com if you need additional information or |
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23 * have any questions. |
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24 */ |
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25 |
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26 package java.nio.file.attribute; |
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27 |
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28 import java.nio.file.*; |
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29 import java.util.List; |
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30 import java.io.IOException; |
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31 |
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32 /** |
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33 * A file attribute view that supports reading or updating a file's Access |
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34 * Control Lists (ACL) or file owner attributes. |
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35 * |
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36 * <p> ACLs are used to specify access rights to file system objects. An ACL is |
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37 * an ordered list of {@link AclEntry access-control-entries}, each specifying a |
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38 * {@link UserPrincipal} and the level of access for that user principal. This |
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39 * file attribute view defines the {@link #getAcl() getAcl}, and {@link |
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40 * #setAcl(List) setAcl} methods to read and write ACLs based on the ACL |
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41 * model specified in <a href="http://www.ietf.org/rfc/rfc3530.txt"><i>RFC 3530: |
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42 * Network File System (NFS) version 4 Protocol</i></a>. This file attribute view |
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43 * is intended for file system implementations that support the NFSv4 ACL model |
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44 * or have a <em>well-defined</em> mapping between the NFSv4 ACL model and the ACL |
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45 * model used by the file system. The details of such mapping are implementation |
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46 * dependent and are therefore unspecified. |
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47 * |
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48 * <p> This class also extends {@code FileOwnerAttributeView} so as to define |
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49 * methods to get and set the file owner. |
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50 * |
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51 * <p> When a file system provides access to a set of {@link FileStore |
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52 * file-systems} that are not homogeneous then only some of the file systems may |
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53 * support ACLs. The {@link FileStore#supportsFileAttributeView |
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54 * supportsFileAttributeView} method can be used to test if a file system |
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55 * supports ACLs. |
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56 * |
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57 * <a name="interop"><h4>Interoperability</h4></a> |
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58 * |
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59 * RFC 3530 allows for special user identities to be used on platforms that |
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60 * support the POSIX defined access permissions. The special user identities |
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61 * are "{@code OWNER@}", "{@code GROUP@}", and "{@code EVERYONE@}". When both |
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62 * the {@code AclFileAttributeView} and the {@link PosixFileAttributeView} |
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63 * are supported then these special user identities may be included in ACL {@link |
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64 * AclEntry entries} that are read or written. The file system's {@link |
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65 * UserPrincipalLookupService} may be used to obtain a {@link UserPrincipal} |
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66 * to represent these special identities by invoking the {@link |
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67 * UserPrincipalLookupService#lookupPrincipalByName lookupPrincipalByName} |
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68 * method. |
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69 * |
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70 * <p> <b>Usage Example:</b> |
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71 * Suppose we wish to add an entry to an existing ACL to grant "joe" access: |
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72 * <pre> |
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73 * // lookup "joe" |
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74 * UserPrincipal joe = file.getFileSystem().getUserPrincipalLookupService() |
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75 * .lookupPrincipalByName("joe"); |
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76 * |
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77 * // get view |
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78 * AclFileAttributeView view = file.newFileAttributeView(AclFileAttributeView.class); |
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79 * |
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80 * // create ACE to give "joe" read access |
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81 * AclEntry entry = AclEntry.newBuilder() |
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82 * .setType(AclEntryType.ALLOW) |
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83 * .setPrincipal(joe) |
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84 * .setPermissions(AclEntryPermission.READ_DATA, AclEntryPermission.READ_ATTRIBUTES) |
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85 * .build(); |
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86 * |
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87 * // read ACL, insert ACE, re-write ACL |
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88 * List<AclEntry> acl = view.getAcl(); |
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89 * acl.add(0, entry); // insert before any DENY entries |
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90 * view.setAcl(acl); |
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91 * </pre> |
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92 * |
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93 * <h4> Dynamic Access </h4> |
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94 * <p> Where dynamic access to file attributes is required, the attributes |
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95 * supported by this attribute view are as follows: |
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96 * <blockquote> |
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97 * <table border="1" cellpadding="8"> |
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98 * <tr> |
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99 * <th> Name </th> |
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100 * <th> Type </th> |
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101 * </tr> |
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102 * <tr> |
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103 * <td> "acl" </td> |
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104 * <td> {@link List}<{@link AclEntry}> </td> |
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105 * </tr> |
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106 * <tr> |
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107 * <td> "owner" </td> |
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108 * <td> {@link UserPrincipal} </td> |
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109 * </tr> |
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110 * </table> |
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111 * </blockquote> |
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112 * |
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113 * <p> The {@link #getAttribute getAttribute} or {@link #readAttributes |
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114 * readAttributes} methods may be used to read the ACL or owner attributes as if |
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115 * by invoking the {@link #getAcl getAcl} or {@link #getOwner getOwner} methods. |
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116 * |
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117 * <p> The {@link #setAttribute setAttribute} method may be used to update the |
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118 * ACL or owner attributes as if by invoking the {@link #setAcl setAcl} or {@link |
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119 * #setOwner setOwner} methods. |
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120 * |
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121 * <h4> Setting the ACL when creating a file </h4> |
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122 * |
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123 * <p> Implementations supporting this attribute view may also support setting |
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124 * the initial ACL when creating a file or directory. The initial ACL |
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125 * may be provided to methods such as {@link Path#createFile createFile} or {@link |
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126 * Path#createDirectory createDirectory} as an {@link FileAttribute} with {@link |
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127 * FileAttribute#name name} {@code "acl:acl"} and a {@link FileAttribute#value |
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128 * value} that is the list of {@code AclEntry} objects. |
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129 * |
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130 * <p> Where an implementation supports an ACL model that differs from the NFSv4 |
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131 * defined ACL model then setting the initial ACL when creating the file must |
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132 * translate the ACL to the model supported by the file system. Methods that |
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133 * create a file should reject (by throwing {@link IOException IOException}) |
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134 * any attempt to create a file that would be less secure as a result of the |
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135 * translation. |
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136 * |
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137 * @since 1.7 |
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138 * @see Attributes#getAcl |
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139 * @see Attributes#setAcl |
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140 */ |
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141 |
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142 public interface AclFileAttributeView |
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143 extends FileOwnerAttributeView |
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144 { |
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145 /** |
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146 * Returns the name of the attribute view. Attribute views of this type |
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147 * have the name {@code "acl"}. |
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148 */ |
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149 @Override |
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150 String name(); |
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151 |
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152 /** |
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153 * Reads the access control list. |
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154 * |
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155 * <p> When the file system uses an ACL model that differs from the NFSv4 |
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156 * defined ACL model, then this method returns an ACL that is the translation |
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157 * of the ACL to the NFSv4 ACL model. |
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158 * |
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159 * <p> The returned list is modifiable so as to facilitate changes to the |
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160 * existing ACL. The {@link #setAcl setAcl} method is used to update |
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161 * the file's ACL attribute. |
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162 * |
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163 * @return An ordered list of {@link AclEntry entries} representing the |
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164 * ACL |
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165 * |
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166 * @throws IOException |
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167 * If an I/O error occurs |
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168 * @throws SecurityException |
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169 * In the case of the default provider, a security manager is |
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170 * installed, and it denies {@link RuntimePermission}<tt>("accessUserInformation")</tt> |
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171 * or its {@link SecurityManager#checkRead(String) checkRead} method |
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172 * denies read access to the file. |
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173 */ |
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174 List<AclEntry> getAcl() throws IOException; |
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175 |
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176 /** |
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177 * Updates (replace) the access control list. |
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178 * |
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179 * <p> Where the file system supports Access Control Lists, and it uses an |
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180 * ACL model that differs from the NFSv4 defined ACL model, then this method |
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181 * must translate the ACL to the model supported by the file system. This |
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182 * method should reject (by throwing {@link IOException IOException}) any |
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183 * attempt to write an ACL that would appear to make the file more secure |
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184 * than would be the case if the ACL were updated. Where an implementation |
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185 * does not support a mapping of {@link AclEntryType#AUDIT} or {@link |
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186 * AclEntryType#ALARM} entries, then this method ignores these entries when |
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187 * writing the ACL. |
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188 * |
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189 * <p> If an ACL entry contains a {@link AclEntry#principal user-principal} |
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190 * that is not associated with the same provider as this attribute view then |
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191 * {@link ProviderMismatchException} is thrown. Additional validation, if |
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192 * any, is implementation dependent. |
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193 * |
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194 * <p> If the file system supports other security related file attributes |
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195 * (such as a file {@link PosixFileAttributes#permissions |
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196 * access-permissions} for example), the updating the access control list |
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197 * may also cause these security related attributes to be updated. |
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198 * |
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199 * @param acl |
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200 * The new access control list |
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201 * |
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202 * @throws IOException |
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203 * If an I/O error occurs or the ACL is invalid |
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204 * @throws SecurityException |
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205 * In the case of the default provider, a security manager is |
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206 * installed, it denies {@link RuntimePermission}<tt>("accessUserInformation")</tt> |
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207 * or its {@link SecurityManager#checkWrite(String) checkWrite} |
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208 * method denies write access to the file. |
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209 */ |
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210 void setAcl(List<AclEntry> acl) throws IOException; |
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211 } |